Ray Optics Method Research Articles

Ray-optical solution for the dyadic Green's function in a rectangular cavity

The ray-optical method, which has been successfully employed for the analysis of diffraction and scattering problems, is used to derive the Green's function in a rectangular cavity. Despite the asymptotic approximations inherent in the method, it is shown that it gives a physical or geometrical insight into the mechanisms of propagation in guiding structures leading to exact or rigorous solutions not always provided by other methods.

Ray method for scattering by small discontinuities in a waveguide

As an improvement on the conventional induced-dipolemoment calculation, a ray-optical method is advocated which provides for obstacle-wall interaction and is not invalidated by short-wavelength approximations. Possible applications to other propagation problems are listed.

Ray-Optical Analysis of Electromagnetic Scattering in Waveguides

The ray-optical method presented previously for the analysis of scalarizable waveguide discontinuity problems is extended to vector scattering problems wherein an incident TE or TM mode excites both mode types. The procedure is illustrated first for reflection of an obliquely incident mode from the open end of a parallel plane waveguide, and is then applied to reflection from an open-ended circular waveguide. Formulas for modal reflection and coupling coefficients are given to various degrees of approximation, depending on whether or not multiple interaction phenomena are considered in addition to the simplest primary diffraction effects. Comparison with data computed from exact solutions for the circular waveguide problem shows that the ray-optical method is remarkably accurate not only in the strongly overmoded but also the dominant mode regimes.

Computerized ray optics method of calculating average value radar cross section

In attempting to estimate the radar cross section of airborne vehicles, it is often only necessary to consider average values of the radar returns. A method of providing a quick estimate of the average bistatic radar cross section of the vehicle components would be useful. Ray optics provides a method of predicting the radar cross section of electrically large, perfectly conducting, simply curved, convex bodies such as spheres, ogives, ellipsoids, etc. This paper extends the method of ray optics to the case of an arbitrary body, which may be concave and/or convex, on which doable reflection and depolarization can occur. The incident radiation on the scattering body is represented by a large number <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(10^{5}-10^{6})</tex> of rays. The rays reflected in a given direction with a given polarization are collected at infinity and combined by phasor addition. For the bodies investigated, this method yields results within <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\pm2</tex> dB of measured results except in small angular regions where trapped waves contribute significantly to the radar return.

Ray-optical techniques for guided waves

While ray-optical methods have been employed for the analysis of high-frequency radiation and scattering problems and also for the study of optical resonators, their use for description of guided modes has been less evident. This paper presents a systematic procedure whereby the asymptotic functional dependences and eigenvalues of modes in uniform and nonuniform guiding structures are deduced by purely ray-optical means, utilizing either the eiconal and transport equations of geometrical optics or a modal consistency argument. The method is illustrated first on the simple example of a homogeneous plane slab, and is then applied to various nonuniform waveguides including an angular sector, a more general taper of either parabolic or hyperbolic shape, and a guide filled with an axially inhomogeneous dielectric. The role of caustics in the latter configurations is emphasized, and stress is placed throughout on a physical interpretation of relevant concepts which retain their validity even under conditions more general than those considered at present.